Flat calibration

A Duet

 in Blog  tagged Ab Light / Adim Controller / dimmer / Flat calibration / PWM

Joining in a duet with the ‘Ab Light’ product that I announced recently, it’s now time to unveil the ‘Adim Controller’.  Adim (for the musically challenged, this is read as ‘A diminished’) is a dimmer for Ab Light.  It could also be used for other 12V devices that would respond well to a PWM power input, including fans and other types of lights.  Adim provides both manual and computer-based control, and can drive up to 1.5 amp loads. The PWM (pulse-width modulation) output operates at 2kHz, meaning that the on/off cycle repeats 2,000 times per second, or every 500 microseconds […]

The Music Series

 in Blog  tagged AbL / Flat calibration / flat light / lunar eclipse

In my last post I explained what flat calibration is and what is required to make it work. In this post I will introduce my solution to the problem, “Ab Light”: The name (in case it isn’t obvious) is a small pun based on my interest in music. “Ab” is read as “A flat”, and this is ‘a flat light’. Ab Light (abbreviated AbL) is based on LED technology, with a light pipe made of a special type of acrylic that is designed to provide even illumination when lit from the edges. I used the same material for the illumination […]

Flat Calibration Explained

 in Blog  tagged Flat calibration / flat frames / flat light source

To properly process an astrophoto the first step in most cases is ‘calibration’. The purpose of calibration is to compensate for various defects in the image sensor and the optical system. Essentially, we capture images that isolate the most common defects and mathematically apply the inverse of the error to each of the raw images we have captured. One part of this calibration is to remove unevenness in the brightness across the frame. This step is called ‘flat calibration’. Unevenness (lack of flatness) can be caused by vignetting of light by the optical system (the image is darker in the […]